The invention relates to a surgical stapling instrument for suturing tissue or organs and more particularly to such an instrument which is sensitive to the pressure being applied to the tissue or organ by the instrument and which is working gap-controlled.
Prior art workers have devised numerous embodiments of the type of surgical stapling instrument to which the improvements of the present invention are directed. Examples of such surgical stapling instruments are taught in U.S. Letters Pat. Nos. 3,080,564; 3,252,643; 3,269,630; 3,275,211; 3,315,863; 3,494,533; 3,589,589 and 3,795,034. All such surgical stapling instruments are intended for use in suturing tissue or organs such as pulmonary tissue, gastric stumps, bronchial stumps, small and large intestines, the stomach, the duodenum and the like. These prior art surgical stapling instruments are, in general, characterized by a fixed anvil or anvil supporting jaw and a movable staple cartridge-carrying jaw. The staple cartridge-carrying jaw is shiftable toward and away from the anvil jaw. The organ or tissue to be sutured is located between the fixed anvil jaw and the shiftable staple cartridge-carrying jaw.
The typical staple cartridge contains staples arranged to provide one or more staple suture lines. The cartridge is also provided with one or more staple drivers which, when shifted toward the fixed jaw of the instrument, will cause the staples to be driven from the cartridge and through the tissue or organ. The staples will be clinched by staple clinching grooves in the anvil portion of the fixed jaw. Finally, each such instrument is typically provided with a staple driver actuator by which the surgeon may cause the staple sutures to be implanted and clinched.
Prior art workers have devised various means to shift the staple cartridge-carrying jaw toward the fixed jaw. The most commonly encountered means is a hand-operated screw mechanism which directly powers the staple cartridge-carrying jaw toward the fixed anvil jaw. It will be understood that, for proper operation of the surgical instrument, the working gap between the staple cartridge-carrying jaw and the anvil jaw, in which the organ or tissue to be sutured is located, should be within the forming limits of the staples. In other words, the staples must be adequately clinched while, on the other hand, they must not be deformed or crushed.
With prior art surgical stapling instruments of the type under consideration, the surgeon simply rotated the screw mechanism (or manipulated some other form of advancing means) to shift the staple cartridge-carrying jaw toward the fixed anvil jaw until a predetermined gap or distance between the jaws, within the working gap of the instrument and its staples, was attained. The difficulty with this arrangement lies in the fact that the thickness and compressibility of organs and tissues vary. Therefore, when the staple cartridge-carrying jaw is driven or shifted to a predetermined distance from the fixed anvil jaw, it is very improbable that a correct compression will be placed on the organ or tissue to be sutured. If the organ or tissue is over-compressed, it can become strangulated and can undergo necroses. On the other hand, if the tissue or organ is under-compressed, hemostasis of the suture line will not be achieved with the accompanying well known undesirable effects.
The surgical instrument of the present invention overcomes this difficulty by driving the staple cartridge-carrying jaw toward the fixed anvil jaw by means of a pressure responsive clutch means. This provides an arrangement wherein the instrument closing and the establishment of the gap of the instrument are controlled by the pressure put upon the organ or tissue by the instrument. With prior art instruments, once the surgeon advanced the staple cartridge-carrying jaw to the predetermined position relative to the fixed anvil jaw, he could be assured that the gap therebetween was within the proper working gap of the instrument and its staples, assuring correct formation of the staple sutures. In the surgical stapling instrument of the present invention, since the closing of the instrument is controlled by the pressure applied to the organ or tissue to be sutured, the gap between the fixed jaw and the staple cartridge-carrying jaw may not fall within the range of the proper working gap of the instrument. As a consequence, the instrument of the present invention is provided with latch means which preclude movement of the staple driver actuator unless the gap of the instrument is within the limits of its proper working gap. Thus, if the gap established in response to the pressure being applied to the organ or tissue does not fall within the proper working gap of the instrument, use of the instrument is contraindicated. The pressure sensitive mechanism which controls the closure of the instrument has a positive drive to open the instrument. The staple driver actuator latch means also assures that the instrument is sequence controlled.